Choose your poison

They've discovered that sun exposure reduces many forms of cancer.
http://www.lewrockwell.com/miller/miller25.html
http://ije.oxfordjournals.org/cgi/content/full/35/2/227
http://news.bbc.co.uk/2/hi/health/7145080.stm

Meanwhile, we're told not to venture out into the sun, or if we do we should cover all exposed flesh and/or use high-SPF suncreens.
I think I'll continue doing what I'm doing. I haven't had a significant sun burn in years.
Sunscreen is good. Some UVB sunlight will penetrate fabrics, and some sunscreen will get worn off in spots. So even if I wear sunscreen as many hours as I spend in the sun, I'll certainly get sufficient vitamin D.

What most articles on this subject leave out is that vitamin D is converted from vitamin C. If you're low on vitamin C, there's nothing to convert to vitamin D. The conversion process makes you less succeptible to sunburn and cancer. So to avoid sunburn, take vitamin C.
The RDA of vitamin C is based on regular patterns of averages. If you're going to spend unusual amounts of time under the sun, you need to take unusual amounts of vitamin C.
My Ultimate Direction bottles have little pockets. Each pocket has a tiny baggie with vitamin C, ibuprofen, and e-caps.

It seems to me that if I had to choose between forms of cancer, I'd rather have skin cancer than lung or colon cancer.